The objective of this study is to demonstrate the effectiveness and tolerability of the buprenorphine transdermal system (BTDS) 20 in comparison to the buprenorphine transdermal system (BTDS) 5 and oxycodone immediate-release in subjects with moderate to severe low back pain currently treated with oral opioids. The double-blind treatment intervention duration is 12 weeks during which time supplemental analgesic medication (acetaminophen, ibuprofen) will be provided to all subjects in addition to study drug.